The present invention relates to devices which aid in the teaching of playing a keyboard by turning on and off lights above each key to indicate keys to be played.
A number of designs have been developed using indicating lights, such as LEDs to indicate the keys on a keyboard to be played. French published Application No. 2,479,516 shows a pad containing light emitting diodes which is positioned above the piano keys with a diode positioned above each key. A red diode is provided for white keys and a green diode for black keys. The application generally describes a microprocessor being coupled to a cassette player to somehow interpret the sounds and illuminate the appropriate key. The details of how this is done do not appear to be disclosed. The volume is used to control the light intensity.
U.S. Pat. No. 4,703,681 shows a keyboard with indicator lights above each key. A special timing circuit is disclosed which lights up the LED corresponding to the key prior to the time it is to be played, thus giving the user advance notice of the transition.
U.S. Pat. No. 4,694,723 shows a keyboard with embedded LEDs above the keys. A ROM pack with stored music is used to provide signals to the LEDs to light them up in accordance with the music to be played. Keyboard depressions are then detected, and compared with the desired timing of the key. An indication is provided to the user of whether the keys are being played properly by comparing the signals sent to the LED and the key depression signals.
U.S. Pat. No. 4,651,612 shows a keyboard with indicating lights above the keys. An auto play data ROM is used to produce signals to the LEDs to light them up and also to generate accompanying musical sounds to go with the keyboard. The key depression signals are compared to the desired depressions as indicated by the LEDs. The accompanying music is either sped up or slowed down to match the speed at which the keyboard is actually being played.
Keyboard synthesizers in other instruments which produce music have been developed. In addition, devices which input digital representations of music to a computer have also been developed. A standard has been developed for the digital communication of such musical information, called the Musical Instrument Digital Interface (MIDI) a copy of which is available from the International MIDI Association, 5316 West 57th Street, Los Angeles, Calif. 90056. Basically, the MIDI standard provides that communication is done serially and asynchronously at a rate of 31.25 kilobaud. Information is transmitted by first transmitting a status byte, followed by two nibbles. The high nibble (first four bits) indicates the type of command. The low nibble indicates one of sixteen channels. A common use for the channels is to assign them to different instruments (piano, violin, drums) reproduced by a synthesizer. Data bytes follow the status byte and are interpreted differently depending upon a particular status byte. For instance, one status byte will indicate that a note should go on, and will be followed by a data byte indicating a digital value of the note and a second data byte indicating the velocity at which a key is depressed to produce that note.
It is desirable to have a simple teaching aid for a keyboard which is compatible with the MIDI standard and does not require additional complicated timing or other circuitry and is useful with different types of keyboard synthesizers and normal pianos.